Detection apparatus

ABSTRACT

The subject invention pertains to an assay device suitable for use in testing samples for the presence of microorganisms. The assay device of the subject invention comprises a housing having two chambers therewithin, each chamber being partially defined by a first filter material and each having a liquid inlet, the device also comprising means for holding the first material in a first or second position, respectively, such that the chambers are either separate or in communication. This arrangement allows assays to be made more accurately, since material that is otherwise retained in the corners of the assay chamber can be simply washed away.

FIELD OF THE INVENTION

This invention relates to apparatus suitable for use in testing liquidsamples for the presence of microorganisms.

BACKGROUND OF THE INVENTION

Apparatus for the detection of microorganisms in liquid samples isknown, the use of which involves the introduction of the sample,optionally followed by wash liquid, and then growth medium, to encouragethe organism to multiply. In some cases, the sample may be an antibioticwhich, if residual material remains, can inhibit the growth of organismsthereby giving false negative results. The difficulty encountered withsuch apparatus is that residual sample may become trapped in corners ofthe apparatus and is difficult to remove.

SUMMARY OF THE INVENTION

The present invention provides simple apparatus, suitable for manualuse, which can obviate the problem described above and provide for bothbiological detection and optimised sterility testing. The novel assaydevice comprises a housing having two chambers therewithin, bothchambers being partially defined by a filter material and each having aliquid inlet, the device comprising also means for holding the filtermaterial in a first or second position, respectively, such that thechambers are either separate or in communication.

In use of the apparatus, the region of contact between the filtermaterial and the chamber division, where residual sample may collectwhile the said means is maintained in the first position, can be simplyand effectively washed by selecting the second position. A furtheradvantage of the novel apparatus is that is it well adapted to the useof sensitive bioluminescence assays, and by contrast with conventionalturbidity observation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic sectional view of a device embodying thepresent invention.

DESCRIPTION OF THE INVENTION

The invention will now be described by way of example only withreference to FIG. 1, which is a schematic sectional view of a deviceembodying the present invention.

FIG. 1 shows a generally cylindrical housing 10 having an internalcylindrical wall 11 that effectively divides the housing into respectivecylindrical and annular chambers 12, 13. These chambers have respectiveliquid inlets 14, 15 (although one inlet may be replaced by an internalcommunication), and are partially defined by a common filter material16.

FIG. 1 shows also a complementary generally cylindrical part 20 that isengageable with the housing 10, suitably by means of complementarycircumferential engagement means 21, e.g., a snap-fit or threadedengagement (if the latter, the housing 10 and part 20 may be heldtogether at all times, in engagement to a greater or lesser degreedefining the first and second positions of the filter material 16, asdiscussed below). The part 20 comprises an internal generallycylindrical wall 22 corresponding to wall 11, and including perforations23 such that the respective generally cylindrical and annular volumes24, 25 are in communication. The part 20 also includes a liquid outlet26.

In use, the housing 10 and part 20 are firmly engaged, such that theirrespective walls 11 and 22 are substantially in contact, and maycompress the filter material 16 therebetween. In this "first" position,the chambers 12 and 13 are separate.

Sample is now introduced through inlet 15 into the chamber 12, andliquid is allowed or caused to drain through the filter material 16 andthen out of the device through the outlet 26.

Sample may have collected at the interface of the wall 11 and the filtermaterial 16, and possibly beyond the wall 11. However, the filtermaterial can now be effectively washed by moving or partiallydisengaging the part 20, so that the filter material 16 is no longerheld in close contact with the wall 11, i.e., in the "second position"and introducing a wash material through inlet 14.

A growth medium may now be introduced through the inlet 15 into thechamber 12, to allow the growth of microorganisms retained on the filtermaterial 16 unless that is inhibited by antibiotic. Following growth,liquid can be removed through the outlet 26.

According to a particularly preferred embodiment of the invention, theinlets 14 and 15 are closed, the housing 10 inverted, and the growthmedium is washed into contact with a second filter material 17 thatpartially defines a member 18 that can be separated from the housing 10,usually by means of a frangible, male-female or other connection at 19.This separable member 18 is suitably in the form of a cuvette that canbe introduced directly into a suitable analytical instrument, orretained by the user for future analysis. By the provision of severalmembers 18 that can be releasably connected to the housing 10, the noveldevice can be used for multiple assays.

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication and the scope of the appended claims.

I claim:
 1. An assay device comprising a housing partially defined by afirst filter material and having two chambers therewithin, said chambersforming an integral part of said housing and each chamber beingpartially defined by said first filter material and each of saidchambers having a liquid inlet, the device also comprising means forholding said filter material in a first or second position,respectively, such that said chambers are either separate or incommunication.
 2. The device according to claim 1, wherein said filterholding means comprises a structure engageable with said housing andproviding said filter holding means according to the degree ofengagement.
 3. The device according to claim 1, in which one chamber issurrounded by the other chamber.
 4. The device according to claim 1,which additionally comprises a separable member partially defined by asecond filter material and in communication with one of said chambers.5. A method for retaining an analyte present in a liquid sample, whichcomprises the steps of:(a) introducing the sample into one of saidchambers of a device according to claim 1 and through said first filtermaterial in the first position; and (b) introducing a wash liquid intothe other chamber, when said first filter material is in the secondposition.
 6. The method according to claim 5, in wherein said method thedevice is as defined in claim 4, which additionally comprises the stepsof inverting said device and separating said separable member, whendesired.
 7. The method according to claim 5, wherein the analyte is amicroorganism.
 8. The method according to claim 7, wherein said methodadditionally comprises the step of introducing a growth medium into thechamber of said device.
 9. The method according to claim 6, wherein theanalyte is a microorganism.
 10. The device according to claim 3, whereinsaid other chamber is annular.